There are several different types of surveys. For example, geodetic surveys cover a large geographic area and attempt to define the exact three-dimensional coordinates (northing, easting and elevation) of points on the earth's surface. Cadastral surveys are typically boundary surveys to define legal or political boundaries on plans.
Another type of survey is associated with a GIS (“Geographical Information System”), which ties assets to spatial data, and these are best derived from a universally acceptable coordinate system such as the GPS. GIS is a type of geographical information system and GIS is the industry acronym for a technology that integrates database information to coordinated maps. A GIS survey is the acquisition of data, which is linked (surveyed to a location) to a (specific) physical location on a map. A GIS creates “intelligent” super-maps for sophisticated planning and analysis. GPS surveys make this survey more economically viable but offer no quality assurance without being integrated or tied into physical monuments the location of which are known.
It is becoming increasingly desirable and attainable to integrate different types of surveys to a country state or provincial grid, or GPS to provide a unified co-ordinate system. However, the monuments used for geodetic and other types of surveys are expensive to place, difficult to maintain and not easily used for many practical survey applications.
Topographical and construction surveys are often tied to independently-adjusted networks of control points, and often to survey monuments used for either cadastral surveys or geodetic networks set by the state or province. In the case of geodetic monuments, they are often buried on right-of-way's to place them in inter-visible locations (so they can be viewed from one to the other). This makes them difficult and expensive to install and/or use.
Surveyors when carrying out a survey will typically mark certain physical locations for the survey, such as the corners of property, by these visible monuments. These monuments are typically secured to the ground or applied to an object, and which then mark a position on the surface of the earth. Early types of monuments were placed on natural objects such as trees, boulders or the like. However, as the need grew for more monuments, which would be more durable, more permanent types of monuments were developed. For example, it is known to provide a monument formed with a metal stake. The stake can then be driven into a suitable substrate such as for example, a rock, or can be set in concrete in the ground. Survey indicia on a top plate or disc on top of the stake provide a reference as to the location of that monument.
The more monuments there are the easier it becomes to establish or re-establish coordinated points in a survey grid or network. It will be appreciated, however, that these types of monuments can be time consuming and costly to manufacture and locate, particularly when several are needed to be located within a given area. For example, monuments are required to be properly located when a new housing subdivision is being formed. These markers are needed so that property lines can be determined. However, it is sometimes difficult to insert or affix these known monuments in places where they are needed. During retracement surveys of a property, only the minimum number of monuments are typically replaced. The vast majority are removed during construction and this can result in disputes over property lines and involve having to perform retracement surveys.
Monuments, including those in towns or cities, are often set or positioned flush or nearly flush with the surrounding ground. Particularly in cold climates where there is a lot of snow and ice on the ground, this may make the locating of a monument by a surveyor particularly difficult, requiring digging through snow and ice to try to find the monument.
To assist in the location of survey monuments, it is known to include a magnet as part of the device. The magnet then may be detected, at least under some conditions, with the use of known types of magnetic detection instruments.
Being positioned flush or almost flush to the ground poses other problems, including the greater risk of being dislodged, displaced or vandalised.
Monuments can also be used in connection with electronic location systems such as the satellite based global positioning systems (GPS systems). Mobile location (e.g. GPS) devices used by individuals, either in their cars or elsewhere are becoming more common. Many of these devices are small hand held devices, which can be easily transported around by an individual. From time to time, to be able to verify that the device, such as a mobile GPS device, is providing accurate readings reference can be made to an existing survey monument. However, it is relatively difficult for the general public to know where to look for such a monument, when they decide they need to calibrate or localize their GPS device or other electronic location device to obtain a quality assurance reading.
Also, GPS is often more meaningful when tied to a local datum (i.e. the co-ordinates to which the region has been typically or traditionally utilizing). Quality assurance of GPS is provided by checking known points to verify a plurality of GPS indicated positions. To do datum transformations, known points must be utilized. Known points are the quickest way to initialize the GPS system and a minimum of four (with a known northing, easting and elevation), 3 dimensional points evenly distributed to the extent of a particular survey is recommended to calibrate or localize a GPS device (convert GPS measured coordinates into local grid co-ordinates) This initialization of a GPS device is a mathematical transformation of the global coordinates by a localization routine to the desired local coordinates. If a GPS device is activated over a monument with known coordinates it initializes much quicker and simultaneously provides the user with verification that it is functioning correctly. The user will feed in the known co-ordinates into the mobile device and then the device will run the localization routine and the device will then be initialized and ready for operation. With the use of GPS devices expanding among members of the general public, most having no survey experience, there is a need to provide an easily accessible and recognizable monument that such individuals can use to assist them in initializing their mobile location or position devices.